Apparatus for on demand production of hydrogen by electrolysis of water

ABSTRACT

Apparatus for on demand production of hydrogen by electrolysis of water including an elongated, tubular housing with a first open end and second open end, wherein the first end is closed with a first lid and the second end is closed with a second lid; a solid rod anode is arranged centrally within said tubular housing and a electrical connector of the rod anode reaches through the first lid; a plurality of tube shaped cathodes is arranged concentrically with respect to the central anode, wherein the tube shaped cathodes are arranged at a certain pitch within the tubular housing and a connector element is provided within the tubular housing for electrically connecting the tube shaped cathodes, wherein at least one connector which is attached to the connector element reaches through the first lid; at least one neutral conductive tube is placed between two consecutive tube shaped cathodes; and at least one neutral conductive tube is placed between the rod anode and the first tube shaped cathode surrounding the rod anode.

FIELD OF THE INVENTION

The present invention relates to an apparatus for on demand productionof hydrogen by electrolysis of water.

BACKGROUND OF THE INVENTION

The environmental effects of pollution and global warming require anenergy source which is easy available and lowers the pollution. There isan ongoing search for another viable, safe and economical source ofalternative fuel compared to fossil fuel. Hydrogen is the most abundantelement in the universe. On earth, 90% of the hydrogen atoms are foundin water and consequently water has been vied as the favorite choice foran endlessly and renewable fuel propulsion source.

Electrolysis is the main procedure that is being used to producehydrogen from water. Each water molecule has two hydrogen atoms and oneoxygen atom. Passing an electric current through water causes the twogases to separate. The oxygen migrates to the positive electrode, theanode and the negative electrode, the cathode, attracts the hydrogen.The resulting process yields twice as much hydrogen as oxygen.

The text book “Fuel From Water”; 12^(th) edition, Copyright © 2008 byMerit Products Inc. Box 6868, Louisville, Ky. 40206; ISBN978-0-945516-04-0, discloses various concepts to obtain hydrogen fromwater and the hydrogen is used for example as an energy source forproviding power for an internal combustion engine.

U.S. Pat. No. 6,533,919 discloses a method for electrolysis of anaqueous solution of an organic fuel. The electrolyte is a solid-statepolymer membrane with anode and cathode catalysts on both surfaces forelectro-oxidation and electro-reduction.

In German Patent Application DE 44 43 476 A1, a method is describedwhich provides an internal combustion engine of a vehicle with hydrogen.The vehicle has an electrolysis device for the production of hydrogenand several storage tanks for hydrogen.

U.S. Pat. RE 38,066 discloses an electrolysis apparatus which has anumber of membrane electrolysis cells. Each of the cells has a membraneformed on both sides with a contact layer. The apparatus, while it iscompact in its design, is also suitable for comparatively high hydrogenproduction rates and can consequently be used particularly flexibly. Acontact plate is respectively arranged on each contact layer. Each ofthe contact plates is formed, on its surface facing the contact layerassigned to it, with a system of ducts for the transport of water and/orgas.

U.S. Pat. No. 7,393,440 provides a system for generating hydrogen gas inan aqueous solution based electrolytic or galvanic cell, wherein thecathode is made from aluminum or an aluminum alloy. In a preferredarrangement the cell is a galvanic cell and cathode is made fromaluminum or aluminum alloy and the anode is made from magnesium ormagnesium alloy

U.S. Pat. No. 7,510,633 discloses an electrolyzer cell for theelectrolysis of water and comprises a cathode of generally tubularconfiguration within which is disposed an anode separated from thecathode by a separation membrane of generally tubular configurationwhich divides the electrolyte chamber into an anode sub-chamber and acathode sub-chamber. An electrolyzer apparatus includes an array ofindividual cells across each of which an electric potential is imposedby a DC generator via electrical leads. Hydrogen gas generated withincells from electrolyte is removed via hydrogen gas take-off lines andhydrogen manifold line. By-product oxygen is removed from cells byoxygen gas take-off lines and oxygen manifold line. The electrolyzerapparatus may be configured to operate either batchwise or in acontinuous electrolyte recycle operation to produce high purity hydrogenat high pressure, e.g., up to about (10,000) psig, without need for gascompressors to compress product hydrogen.

US-Patent Application 2009/0078568 relates to an on-demand hydrogen gasgeneration device, suitable for use in a fuel cell, which utilizes waterelectrolysis, and more particularly galvanic cell corrosion, and/or achemical hydride reaction, to produce hydrogen gas. The presentdisclosure additionally relates to such a device that comprises aswitching mechanism that has an electrical current passing therethroughand that repeatedly and reversibly moves between a first position and asecond position when exposed to pressure differential resulting fromhydrogen gas generation, in order to alter the rate, at which hydrogengas is generated, such that hydrogen gas is generated on an as-neededbasis for a fuel cell connected thereto, and/or ensure a substantiallyconstant flow of hydrogen gas is released therefrom. The presentdisclosure additionally or alternatively relates to such an on-demandhydrogen gas generation device that comprises a gas management systemdesigned to maximize the release or evolution of hydrogen gas, and inparticular dry hydrogen gas, therefrom once it has been formed, thusmaximizing hydrogen gas output. The present disclosure is still furtherdirected to a fuel cell comprising such an on-demand hydrogen gasgeneration device, and in particular to a fuel cell designed forsmall-scale applications.

International Patent Application WO 2008/154721 discloses a processencompassing hydrogen and oxygen gases as a partial fuel source whenutilized together with a fossil-based fuel to power conventionalinternal combustion engines. Hydrogen and oxygen gases are produced byelectrolysis in an electrolyzer unit(s), on-demand and on-board avehicle, or in stationary applications, eliminating the need ofhighly-pressurized hydrogen storage tanks. When said gases areintroduced into the combustion chamber of the engine, via the air intakeassembly, they increase the efficiency of the combustion burn byenriching the air to fuel ratio, resulting in a reduction of thefossil-based fuels required for optimum engine performance, said gaseseffectively becoming a partial hybrid fuel source. The process includesscalability for all size and types of installations, cold-weatherapplications and longer operating capabilities. As an additionalbenefit, in direct correlation, this process reduces carbon dioxideemissions, and, in varying quantities, other greenhouse gas emissions.

Chinese Patent Application CN 101289747 relates to a hydrogen generatingdevice, in particular to a generating device for automobile hydrogenfuel energy. The device comprises a storage battery cell and ahydrogen-oxygen generator, wherein a hydrogen outlet and an oxygenoutlet are respectively communicated with a combustion cylinder; thehydrogen-oxygen generator is an SPE technology hydrogen-oxygen generatorfor water electrolysis and purification. By providing an automobileengine with hydrogen and oxygen generated in water electrolysis andpurification as automobile auxiliary energy, the device can save 20percent of fuel and reduce the emission of harmful gas, which isbeneficial to environment protection. The application of the device doesnot need to change any main structure of an automobile and can becarried out directly on line. The device has the advantages of nopollution, high efficiency, good safety performance and convenientoperation, which can be used in all weather conditions

Japanese Patent Application JP 2008208722 discloses a water electrolysiscell comprising a pair of separators, a solid polymer electrolyticmembrane provided between a pair of the separators and having an anodeside electrode and a cathode side electrode formed on both surfaces. Thefeed conductor is interposed between the solid high polymer membrane andthe separator. The electrode forming surface is formed except a sitewhere the gas pool of the gas (gaseous hydrogen or gaseous oxygen)produced by the water electrolysis.

US Patent Application US 2007/0272548 A1 discloses an electrode assemblyfor use in an electrochemical cell, said electrode being in theproportions of a pyramid with the proportions of the pyramidal shapebeing determined by a specific formula where the height is multiplied bya figure between 1 and 2 to determine the four side lengths and theheight is multiplied by a figure between 1.20 and 2.22 to determine thefour base lengths.

US Patent Application US 2009/0139856 A1 discloses a cell assembly and avertically disposed electrode stack within the cell chamber for theelectrolysis of water to produce hydrogen and oxygen upon theapplication of electric current to the electrodes. The cell assembly isarranged to contain an electrode stack immersed in water, the stackconsisting of at least two electrodes in the form of or having the shapeof quadric surfaces such as cones or cylinders. The electrodes aremounted in close concentric proximity to one another and are positionedby support posts which may also serve as electrical connections and aremounted at the base of the cell chamber and extend upwardly through thebase of each electrode. A lip structure to assist in gas dispersementdisposed about the upper edge of the upper electrode is also disclosed.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus for ondemand production of hydrogen by electrolysis of water, which is easyand save to operate, has a compact design and ensures the highproduction rate of hydrogen.

The present invention provides an apparatus for on demand production ofhydrogen by electrolysis of water comprising:

an elongated, tubular housing with a first open end and second open end,wherein the first end is closed with a first lid and the second end isclosed with a second lid;

a solid rod anode is arranged centrally within said tubular housing anda electrical connector of the rod anode reaches through the first lid;

a plurality of tube shaped cathodes is arranged concentrically withrespect to the central anode, wherein the tube shaped cathodes arearranged at a certain pitch within the tubular housing and a connectorelement is provided within the tubular housing for electricallyconnecting the tube shaped cathodes, wherein at least one connectorwhich is attached to the connector element reaches through the firstlid;

at least one neutral conductive tube is placed between two consecutivetube shaped cathodes; and

at least one neutral conductive tube is placed between the rod anode andthe first tube shaped cathode surrounding the rod anode.

Each of the tube shaped cathodes has a plurality of extensions which areconnected to the connector element. A first comb-shaped spacer structureis provided under the first lid. The first comb-shaped spacer structurehas a central opening for the solid rod anode and a plurality of spacerswith which the concentric arrangement of the tube shaped cathodes andneutral conductive tubes is achieved The tube shaped cathodes andneutral conductive tubes are concentrically arranged with respect to thecentral anode. In order to establish a electrical connection to tubeshaped cathodes the first comb-shaped spacer structure has plurality ofcutouts, which enable passage of the extensions of the tube shapedcathodes to the connector element.

The first comb-shaped spacer structure is formed on a carrier, which hasa plurality of passage openings for hydrogen. Additionally, the carrierholds the connector element on the opposite side of the firstcomb-shaped spacer structure. A second comb-shaped spacer structure isformed on an inward surface of the second lid. The comb-shaped structurehas a central seating for the solid rod anode. The comb-shaped spacerstructure provides spacers for the concentric arrangement of the tubeshaped cathodes and neutral conductive tubes with respect to the centralanode. A plurality of notches is formed on the first comb-shaped spacerstructure and the second comb-shaped spacer structure. The notchesprovide a fixation for the tube shaped cathodes and neutral conductivetubes.

The tubular housing, the first lid and the second lid are formed ofelectrically isolating material. Additionally, the first comb-shapedspacer structure is formed on a carrier, the carrier itself and thesecond comb-shaped spacer structure which is formed on an inward surfaceof the second lid are made from electrically isolating material.Preferably, the electrically isolating material is polycarbonate.

A supply or water is provided thought a nozzle in the second lid. Thefirst lid has an outlet nozzle for the hydrogen generated within thetubular housing. The first lid has a cylindrical extension surroundingthe electrical connector of the rod anode. The cylindrical extension hasmounted an outlet for gas produced at the anode.

The tube shaped cathodes and the neutral conductive tubes have a wallthickness of approximately 1 mm. The massive rod anode, the tube shapedcathodes and the neutral conductive tubes are made from steel, stainlesssteel, aluminum, palladium or titanium.

In further embodiment of the inventive apparatus has an elongated,tubular housing with a first open end and second open end, wherein thefirst end is closed with a first lid and the second end is closed with asecond lid. The tubular housing, the first lid and the second lid aremade from an electrically isolating material. A solid rod anode isarranged centrally within said tubular housing. An electrical connectorof the rod anode reaches through the first lid.

A plurality of tube shaped cathodes is arranged concentrically withrespect to the central anode. The tube shaped cathodes are arranged at acertain pitch within the tubular housing. A connector element isprovided within the tubular housing for electrically connecting the tubeshaped cathodes, wherein two connectors which are attached to theconnector element reach through the first lid. The connector for thecentral anode is connected to a power supply. The two connectors for thetube shaped cathodes are connected to the power supply as well.

Three neutral conductive tubes are placed between the rod anode and thefirst tube shaped cathode surrounding the rod anode. Three neutralconductive tubes are placed between every two of consecutive tube shapedcathodes arranged inside the tube shaped housing.

The design of the inventive apparatus is of tubular nape and adapted toseparate hydrogen from the gasses produced around the rod anode. Inorder to do so a first neutral tube surrounds the rod anode. Therebygases produced around the rod anode are separated from hydrogen.

As mentioned above the most advantageous design is that there are alwaysthree neutral tubes between the tube-shaped cathodes and the solid rodanode in the center of the tubular housing.

In the following we describe one embodiment of the apparatus for the ondemand production of hydrogen. It is clear for a skilled person thatthis embodiment is not regarded as a limitation of the invention. Thisspecific arrangement comprises a total of 35 tubes wherein each of thetubes has a wall thickness of 1 mm. The 35 tubes comprise 8 tube shapedcathodes and 27 neutral conductive tubes. In the center of the apparatusone rod solid anode is positioned which has a diameter of 1 cm. All ofwhich are held in place by polycarbonate spacer to keep a requireddistance between them. These spacers are found both in the bottom lid ofthe tube through which water is also introduced into unit, as well asthe lid assembly. A required distance would be between 1 mm and 6 mm.

As mentioned above the number of the tube shaped cathodes, the number ofthe neutral conductive tubes and the distance between them depends ofthe required production rate of hydrogen.

As mentioned above, the housing wall of the tubular housing and thehousing wall of the first and second lid made of non conductivematerial. At temperatures below freezing an anti freeze agent can beadded to a water reservoir and/or the apparatus for the electrolysis.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will describe the apparatus for economicallyforming packing unit layers according to the present invention in moredetail and its advantages with reference to the accompanying drawings,in which:

FIG. 1 is a perspective view of a preferred embodiment of the apparatusfor electrolysis of water and the production of hydrogen for further usein an energy producing system;

FIG. 2 is a perspective view of the solid rod anode which is centrallyarranged in the tubular housing;

FIG. 3 is a perspective view of the top portion of the apparatus,wherein the tube shaped cathodes and the electric connection to the tubeshaped cathodes is visible;

FIG. 4 is a perspective view of second lid, closing the second end ofthe tubular housing and having a comb-shaped spacer structure for thepositioning and aligning the tube shaped cathodes and the neutralconductive tubes;

FIG. 5 is a perspective view of the first comb-shaped spacer structurewhich is arranged under the first lid;

FIG. 6 is a perspective view of the concentric arrangement of aplurality of tube shaped cathodes;

FIG. 7 is a perspective view from the top onto the carrier for thecomb-shaped spacer structure, wherein the carrier is under the firstlid;

FIG. 8 is a perspective top view onto the first lid;

FIG. 9 is a perspective bottom view onto the first lid; and

FIG. 10 is a schematic view of the inventive apparatus in combinationwith an internal combustion engine.

DETAILED DESCRIPTION OF THE INVENTION

Identical reference numerals are used for the same or equivalentelements of the invention. Furthermore, only reference numerals areshown in the drawings which are necessary for the description of eachfigure for clarity.

FIG. 1 is a perspective view of a preferred embodiment of the apparatus1 for electrolysis of water and the production of hydrogen. The producedhydrogen is used as an on demand energy source. The apparatus 1 is madeof an elongated tubular housing 2. The elongated tubular housing 2 ishas a first end 2 ₁ and a second end 2 ₂. The elongated tubular housing2 is closed at the first end 2 ₁ with a first lid 4 and at the secondend 2 ₂ with a second lid 6.

The first lid 4 has an outlet nozzle 3 for the hydrogen generated withinsaid elongated tubular housing 2. The second lid 6 has an inlet nozzle 5for water in order to assure that a certain water level is maintainedwithin said elongated tubular housing 2. A connector 11, which is usedfor the attachment of a power supply to the rod anode 8 (see FIG. 2),reaches through the first lid 4. Additionally, at least one furtherconnector 12 is provided, which is in electrical contact with the tubeshaped cathodes 20 (see FIG. 6), arranged inside the elongated housing2. According to the embodiment shown in FIG. 1 there are two furtherconnectors 12 through which the electric power is supplied to the tubeshaped cathodes 20. The tubular housing 2, the first lid 4 and thesecond lid 6 is made from electrically isolating material. The preferredelectrically isolating material is polycarbonate.

FIG. 2 is a perspective view of the solid rod anode 8 which is centrallyarranged in the elongated tubular housing 2. The connector 11 isdirectly mounted to the massive rod anode 8 which has a diameter D.According to a preferred embodiment of the invention the diameter D ofthe massive rod anode 8 is 1 cm. The massive rod anode 8 ant theconnector 11 can be formed from a massive, one piece element. A tappedtread 11A is provided on the connector 11 in order to ensure a securepower supply.

A perspective top view of the apparatus 1 for on demand production ofhydrogen by electrolysis of water is shown in FIG. 3. The first end 2 ₁of the elongated housing 2 is closed with a first lid 4 (shown in dashedlines in FIG. 3). Inside the elongated housing 2 a plurality of tubeshaped cathodes 20 are arranged around the massive rod anode 8. Betweentwo consecutive tube shaped cathodes 20 at least one neutral conductivetube 22 is placed The arrangement of the tube shaped cathodes 20 is suchthat the tube shaped cathodes 20 are arranged at a certain pitch withinthe tubular housing 2. In order to provide electrical power to the tubeshaped cathodes 20 each of the tube shaped cathodes 20 is provided withat least one extension 21. The extensions 21 of the tube shaped cathodes20 are connected to a connector element 23.

According to a preferred embodiment of the present invention threeneutral conductive tubes 22 are placed between two consecutive tubeshaped cathodes 20. The connector element 23 has the form of a cross andis isolated from the connector 11 of the rod anode 8. The connectorcarries at least one connector 12 which is mounted to the connectorelement 23 and being in contact with the extensions 21 of the tubeshaped cathodes 20. The connector 23 is arranged under the first lid 4.

As mentioned in the specification with regard to FIG. 8 the first lid 4has a central opening 24 through which the connector 11 of the rod anode8 reaches. According to the embodiment shown in FIG. 3 the first lid 4has two additional openings 25. Through each of the openings 25 oneconnector 12 reaches for the tube shaped cathodes 20. The first lid 4has an outlet nozzle 3 for the generated hydrogen, wherein the outletnozzle 3 is mounted to a further opening 26 in the first lid 4.Additionally, the first lid 4 has a cylindrical extension 27 whichsurrounds the electrical connector 11 of the rod anode 8. An outlet 28for gas produced at and around the rod anode is attached to thecylindrical extension 27.

FIG. 4 is a perspective view of second lid 6, closing the second end 2 ₂of the elongated tubular housing 2. A comb-shaped spacer structure 13 isformed on an inward surface 9 of the second lid 6. The comb-shapedspacer structure 13 assists the positioning and aligning of the tubeshaped cathodes 20 and the neutral conductive tubes 22 inside theelongated tubular housing 2. The comb-shaped spacer structure 13 has acentral seating 14 for the solid rod anode 8. The comb-shaped spacerstructure 13 provides equidistant spacers for the concentric arrangementof the tube shaped cathodes 20 and the neutral conductive tubes 22 withrespect to the central rod anode 8. The second comb-shaped spacerstructure 13 has a plurality of concentrically arranged notches 16 forholding the tube shaped cathodes 20 and the neutral conductive tubes 22in place.

FIG. 5 is a perspective view of the first comb-shaped spacer structure30 which is arranged under the first lid 4. The first comb-shaped spacerstructure 30 has a central opening 31 for the solid rod anode 8 and aplurality of spacers 32 for the concentric arrangement of the tubeshaped cathodes 20 and neutral conductive tubes 22 with respect to thecentral rod anode 8. The first comb-shaped spacer structure 30 hasplurality of cutouts 33, which enable passage of the extensions 21 ofthe tube shaped cathodes 20 to the connector element 23. The firstcomb-shaped spacer structure 30 is formed on a carrier 34. The carrier34 has a plurality of passage openings 35 for hydrogen. Additionally,the carrier 34 holds on the opposite side of the first comb-shapedspacer structure 30 the connector element 23. The first comb-shapedspacer structure 30 has as well a plurality of concentrically arrangednotches 36 which correspond to the concentrically arranged notches 16 ofthe second comb-shaped spacer structure 13. The notches 36 of the firstcomb-shaped spacer structure 30 and the notches 16 of the secondcomb-shaped spacer structure 13 are necessary for holding the tubeshaped cathodes 20 and the neutral conductive tubes 22 in place.

FIG. 6 is a perspective view of the concentric arrangement of the tubeshaped cathodes 20. According to a preferred embodiment eight tubeshaped cathodes 20 ₁, 20 ₂, . . . , 20 ₈ are arranged concentricallywith respect to a central massive rod anode (not shown here). Theextensions 21 of the tube shaped cathodes 20 ₁, 20 ₂, . . . , 20 ₈ forma cross, which corresponds to the connector element 23 to which theextensions 21 are connected. From the tube shaped cathodes 20 ₁, whichis the closest one to the massive rod anode (not shown here), theoutermost tube shaped cathodes 20 ₈ in the concentric arrangement of thetube shaped cathodes 20 ₁, 20 ₂, . . . , 20 ₈ the diameter of the tubeshaped cathodes 20 ₁, 20 ₂, . . . , 20 ₈ increases. According topreferred embodiment, the wall thickness of the tube shaped cathodes 20₁, 20 ₂, . . . , 20 ₈ is about 1 mm.

FIG. 7 is a perspective view from the top onto the carrier 34 for firstthe comb-shaped spacer structure 10. The carrier 34 holds the connectorelement 23 (not shown here). The first comb-shaped spacer structure 30has plurality of cutouts 33 which correspond to openings 40 formed inthe carrier 34. The openings 40 enable passage of the extensions 21 ofthe tube shaped cathodes 20 in order to be in electrical contact withthe connector element 23. The first comb-shaped spacer structure 30 isformed on a carrier 34. Additionally, the carrier 34 has a plurality ofpassage openings 35 for hydrogen. The first comb-shaped spacer structure30 has as well a plurality of concentrically arranged notches 36 whichcorrespond to the concentrically arranged notches 16 of the comb-shapedspacer structure 13 on the bottom 9 of the second lid 6 in order toensure am exact and secure positioning of the tube shaped cathodes 20and neutral conductive tubes 22 inside the elongated tubular housing 2.

FIG. 8 is a perspective top view onto the first lid 4. The first lid 4has a central opening 24 through which the connector 11 of the rod anode8 reaches the outside of the elongated housing. Two additional openings25 are arranged diametrically with respect to the central opening 24.Through each of the openings 25 one connector 12 reaches. As mentionedabove, each of the connectors 12 provide an electric connection via theconnector element 23 to the tube shaped cathodes 20. The opening 26 isformed in the first lid 4 for the mounting of the outlet nozzle 3 ofhydrogen the generated during the electrolysis process.

FIG. 9 is a bottom view of the first lid 4. The cylindrical extension27, which surrounds the electrical connector 11 of the rod anode 8,stretches across the bottom 36 of the first lid 4. The portion of thecylindrical extension 27, which stretches across the bottom 36 of thefirst lid 4, is in mechanical contact with the neutral conductive tube22 adjoining the rod anode 8. The effect is, that first neutral tube 22surrounding the rod anode 8 together with the cylindrical extension 27seal in the gases produced around the rod anode 8 during theelectrolysis process.

FIG. 10 is a schematic arrangement of the inventive apparatus 1 incombination with an internal combustion engine 45. It is obvious for aperson skilled in the art that the invention is not limited to the useof the apparatus for on demand production of hydrogen by electrolysis ofwater in combination with an internal combustion engine. The inventiveapparatus can be used together all energy users, which can use theenergy content of hydrogen and obtain another energy form.

The inventive apparatus 1 used in connection with an internal combustionengine 45 is provided with a duct 43 from a reservoir 42. Via duct 43the apparatus 1 receives the required water supply in order to maintainthe water level constant within is elongated housing 2. The duct 43 tothe apparatus 1 is mounted to the inlet nozzle 5 on the second lid 6. Aspecial voltage and a special current are applied by the power supply 44to the apparatus 1 via the connectors 11 and 12. The connector 11 isconnected to the rod anode 8 and the two connectors 12 are connectedwith the tube shaped cathodes 20. A duct 41 is mounted to the outletnozzle 3. The duct 41 transports the hydrogen generated within saidelongated tubular housing 2 to the internal combustion engine 45.

It is explicitly noted, that the dimensions of the rod anode 8, thedimensions and numbers of the tube shaped cathodes 20, the dimensionsand numbers of the neutral conductive tubes 21 and the selection of thematerial for the elongated housing 2, the first lid 4, the second lid 6and the first and second comb-shaped spacer structure 30 and 13, do notlimit the scope of the present invention.

The invention has been described with reference to a preferredembodiment. It goes without saying for a person skilled in the art thatchanges and modifications can be made without leaving the scope ofprotection of the appended claims.

1. Apparatus for on demand production of hydrogen by electrolysis ofwater comprising: an elongated, tubular housing with a first open endand second open end, wherein the first end is closed by a first lid andthe second end is closed by a second lid; a solid rod anode arrangedcentrally within said tubular housing and a electrical connector of therod anode reaches through the first lid; a plurality of tube shapedcathodes arranged concentrically with respect to the central anode,wherein the tube shaped cathodes are arranged at a certain pitch withinthe tubular housing and a connector element is provided within thetubular housing for electrically connecting the tube shaped cathodes,wherein at least one connector attached to the connector element reachesthrough the first lid; at least one neutral conductive tube locatedbetween two consecutive tube shaped cathodes; and at least one neutralconductive tube located between the rod anode and the first tube shapedcathode surrounding the rod anode.
 2. Apparatus according to claim 1,wherein each of the tube shaped cathodes has a plurality of extensionswhich are connected to the connector element.
 3. Apparatus according toclaim 2, wherein a first comb-shaped spacer structure is arranged underthe first lid, the first comb-shaped spacer structure has a centralopening for the solid rod anode and a plurality of spacers for theconcentric arrangement of the tube shaped cathodes and neutralconductive tubes with respect to the central anode and the firstcomb-shaped spacer structure has plurality of cutouts, which enablepassage of the extensions of the tube shaped cathodes to the connectorelement.
 4. Apparatus according to claim 2, wherein the firstcomb-shaped spacer structure is formed on a carrier, which has aplurality of passage openings for hydrogen and holds the connectorelement on the opposite side of the first comb-shaped spacer structure.5. Apparatus according to claim 4, wherein the first comb-shaped spacerstructure and the carrier are made from electrically isolating material.6. Apparatus according to claim 5, wherein the electrically isolatingmaterial is polycarbonate.
 7. Apparatus according to claim 1, whereinthe first lid has an outlet nozzle for the generated hydrogen. 8.Apparatus according to claim 1, wherein the second lid has an inletnozzle for water.
 9. Apparatus according to claim 1, wherein a secondcomb-shaped spacer structure is formed on an inward surface of thesecond lid and the comb-shaped spacer structure has a central seatingfor the solid rod anode.
 10. Apparatus according to claim 9, wherein thecomb-shaped spacer structure provides spacers for the concentricarrangement of the tube shaped cathodes and neutral conductive tubeswith respect to the central anode.
 11. Apparatus according to claim 1,wherein the tubular housing, the first lid and the second lid are madefrom electrically isolating material.
 12. Apparatus according to claim11, wherein the electrically isolating material is polycarbonate. 13.Apparatus according to claim 1, wherein the first lid has a cylindricalextension surrounding the electrical connector of the rod anode and anoutlet for gas produced at the anode is attached to the cylindricalextension.
 14. Apparatus according to claim 1, wherein the massive rodanode has a diameter of approximately 1 cm.
 15. Apparatus according toclaim 1, wherein tube shaped cathodes and the neutral conductive tubeshave a wall thickness of approximately 1 mm.
 16. Apparatus according toclaim 1, wherein the massive rod anode, the tube shaped cathodes and theneutral conductive tubes are made from steel, stainless steel, aluminum,palladium or titanium.
 17. Apparatus for on demand production ofhydrogen by electrolysis of water comprising: an elongated, tubularhousing with a first open end and second open end, wherein the first endis closed by a first lid and the second end is closed by a second lidand the tubular housing, the first lid and the second lid being madefrom an electrically isolating material; a solid rod anode arrangedcentrally within said tubular housing and a electrical connector of therod anode reaches through the first lid; a plurality of tube shapedcathodes arranged concentrically with respect to the central anode,wherein the tube shaped cathodes are arranged at a certain pitch withinthe tubular housing and a connector element is provided within thetubular housing for electrically connecting the tube shaped cathodes,wherein two connectors which are attached to the connector element reachthrough the first lid; and three neutral conductive tubes locatedbetween the rod anode and the first tube shaped cathode surrounding therod anode and three neutral conductive tubes are located between everytwo of consecutive tube shaped cathodes arranged in the tube shapedhousing.
 18. Apparatus for on demand production of hydrogen byelectrolysis of water comprising: an elongated, tubular housing with afirst open end and second open end, wherein the first end is closed witha first lid and the second end is closed with a second lid and thetubular housing, the first lid and the second lid being made from anelectrically isolating material; a solid rod anode is arranged centrallywithin said tubular housing and a electrical connector of the rod anodereaches through the first lid; a plurality of tube shaped cathodesarranged concentrically with respect to the central anode, wherein thetube shaped cathodes are arranged at a certain pitch within the tubularhousing and a connector element is provided within the tubular housingfor electrically connecting the tube shaped cathodes, wherein at leastone connector attached to the connector element reaches through thefirst lid; three neutral conductive tubes located between the rod anodeand the first tube shaped cathode surrounding the rod anode and threeneutral conductive tubes are located between every two of consecutivetube shaped cathodes arranged inside the tube shaped housing; a secondcomb-shaped spacer structure formed on an inward surface of the secondlid and the comb-shaped structure has a central seating for the solidrod anode and a plurality of concentrically arranged notches for holdingthe tube shaped cathodes and the neutral conductive tubes in place; afirst comb-shaped spacer structure arranged under the first lid, thefirst comb-shaped spacer structure has a central opening for the solidrod anode and a plurality of notches for holding the tube shapedcathodes and neutral conductive tubes in place; and the firstcomb-shaped spacer structure having plurality of cutouts enablingpassage of the extensions of the tube shaped cathodes to the connectorelement.